Peanut allergy: clinical and immunologic characteristics. A case review study.
Principal Investigator:
R. Borici-Mazi, MD, FRCPC
Division of Allergy and Immunology
Tel 613 544 3310 ext. 3328, Fax 613 546-1572
rb62@queensu.ca
Rationale: The prevalence of food allergy in children younger than 5 years of age is 6-8% and food
allergies affect 3.5-4% of entire populations. Peanut allergy is one of the most frequent food allergies
and well known to cause severe reactions, most of which are mostly encountered prior to the diagnosis
of the condition and afterwards as a result of unpredicted accidental exposures.
Multiple research efforts have looked at different condition modifying treatment options for peanut
allergy. A few studies have looked at peanut desensitization and immunotherapy with promising results.
However, these procedures are being carried at research level and not yet approved for clinical practice.
As well, the role of biological agents such as Omalizumab has been investigated but not currently
considered for clinical practice.
Therefore, the management of peanut allergy focuses on the precise diagnosis and implementation of
strict avoidance measures to prevent accidental exposures to peanut and frequent re assessments to
determine the chances to outgrow this condition. These interventions lead to significant life style
modifications involving the peanut allergic patient and his/her social circle.
Twenty percent of peanut allergic patient may outgrow the peanut allergy. Several studies have
demonstrated that peanut allergen is composed of several components with different bearing in clinical
presentation of peanut allergy and perhaps natural history of the condition. A few European studies
have demonstrated that the coexistence of pollen allergy such as birch and perhaps grass pollen allergy
or sensitization may predict a milder form of this condition and perhaps a faster recovery. The
coexistence of pollen allergy increases the likelihood of sensitization to Arah 8 and 9, as compared to
high rates of Arah 1, 2, 3 sensitizations encountered in peanut allergic patients who lack the pollen
allergy. As well sensitization to Arah 2 predicts future peanut anaphylaxis.
Kingston and catchment area is characterized by a great prevalence of outdoor pollen allergy. Therefore,
it is expected that, similarly to Northern European countries, a great proportion of peanut allergic
patients have a concomitant pollen allergy, which may predict a milder and faster to recover condition.
The complete peanut component diagnostic testing(Arah 1,2 , 3, 8, 9) is not currently being used in
clinical practice to manage the peanut allergic patients.
The aim of this study will be to investigate the immunologic characteristics of peanut allergic patients in
Kingston and Catchment area via peanut component diagnostics (Arah 2) in relationship with their
clinical presentation. This study will enable us to identify predictors of longevity of peanut allergy
condition as well as determine the frequency of future assessments.
Study population: This study will include patients with a prior diagnosis of peanut allergy/sensitization
based on positive history of symptoms upon exposure to peanut and previous positive skin testing and/
or whole peanut specific IgE under 18 years of age seen in Outpatient Allergy Clinic at Hotel Dieu
Hospital Kingston. We will also include patients with a new diagnosis of peanut allergy during the study
period.
Methods: we will conduct a chart review of patients with prior diagnosis of peanut allergy/sensitization.
A standardized electronic data collection form will be created. Data (age, sex, previous reactions to
peanut exposure (before and after the diagnosis), peanut skin testing results, peanut specific IgE and
Arah 2 , peanut challenges when available, skin testing to seasonal pollen (Birch) coexistent atopic
dermatitis, asthma, perennial allergic rhinitis, other food allergies (tree nut allergy versus others, oral
allergy syndrome), family history (parents and siblings) of asthma, atopic dermatitis and rhinitis will be
retrieved from patients’ charts. Characteristics of study population will be described as percentages or
median values with interquartile ranges. The Spearman rank correlation analysis will be used to
determine correlation coefficients. The frequencies of asthma, allergic rhinitis, other food allergies, and
other qualitative variables will be compared by using the x2 and Fisher exact tests.
The Innovation: This will bring new information on the patterns of allergy and /or sensitization to peanut
in our area, with heightened pollen exposure. We predict that a great proportion of peanut allergic
patients will demonstrate concomitant pollen allergy (more Birch than Grass pollen) predicting milder
and faster to outgrow peanut allergy condition in comparison to patients who lack the pollen
allergy/sensitization. We will use this information to determine novel predictors for assessing the
longevity of peanut allergy as well as determine the frequency of future evaluations. Eventually, this
study will assist in establishing new cut off values for peanut skin testing site and specific IgE to
determine the outcome of future office peanut food challenges. This would bring a change in current
practice, since we predict that patients with concomitant pollen allergy will likely demonstrate higher
chance of passing an off ice peanut challenge despite demonstrating positive peanut specific IgE
performed with whole peanut extract that we use nowadays. This will greatly improve the quality of life
for patients and their families living with peanut allergy diagnosis.